Emergency power operation control for hydraulic elevators



United States Patent [72] lnventor Richard K. Swartzell Toledo, Ohio [2]] Appl. No. 758,298

[22] Filed Sept. 9, 1968 [45] Patented Oct. 6, 1970 [73] Assignee Reliance Electric Company Toledo, Ohio a corporation of Delaware [54] EMERGENCY POWER OPERATION CONTROL FOR HYDRAULIC ELEVATORS 8 Claims, 2 Drawing Figs.

[52] U.S. Cl. 187/29 [5i] Int. Cl. B66b l/04 [50] Field or Search 187/29 [56] References Cited UNITED STATES PATENTS 3,369,633 2/1968 R. F. Martin 187/29 Primary Examiner-Cris L. Rader Assistant Examiner-W. E. Duncanson, Jr. Attorney-Wilson and Fraser ABSTRACT: A hydraulic elevator control which modifies conventional controls while connected to a secondary power source to run the car automatically, when above a lower landing, under the influence of gravity to said lower landing. The system requires only limited power and can block operation of the pump motor and control circuits unnecessary to down travel while the secondary source is supplying power. Control of descent is through operation of down valve solenoid and its normal control means when the secondary source is connected to the system.

Patented Sheet 1 PLUNGER JACK FIGQ i I NVEN TOR.

RICHARD K. SWARTZELL ATTORNEYS Patented Oct. 6, 1970 3,532,186

Sheet 3 of 2 I87 U I 88\ 1r I I INT UL 32 um L WP? I m s gq 33 SU-i6,?3,24 i so 34 so-mzq 21 :04 9p OP cL M CLT'FGS I" 3H fimgg ,'-|r36 IO (1 o P 02 37 U DOOR CONTROLS 3a 'TIF 39 9 A 1|SELECTOR DRIVE EH10 HMJIVLEVEL U 4ILU4AIQIZ4 Lu L U 98 T TL P ZONE ALDQF-QLDQA a l L T LEVEL DOWN T IL 0 05 TC DCL 46 TC 47 DIRECTION SELECTING 52 AND LOCKING CAR sLowDowN CONTROL 53 HALL cALL REGISTRATION 55 HALL LANTERN CONTROL 5e RICHARD K SWARTZELL ATTORNEYS EMERGENCY POWER OPERATION CONTROL FOR HYDRAULIC ELEVATORS BACKGROUND OF THE INVENTION This invention relates to elevator controls and more particularly to controls for hydraulic elevators.

Heretofore it has been known to provide means for moving elevators to a main floor when the normal source of power fails and an alternative source of power of a magnitude to drive one or more hoist motors is connected to the system. Usually the application of emergency power under these circumstances causes a selection of individual cars for travel to a main floor for shutdown as shown in Robertson U.S. Pat. No. 2,968,364 ofJanuary I7, 1961.

This invention enables hydraulic elevators in a system for which the main power source has failed to be sent to a lower floor by energizing appropriate control circuits with an auxiliary power source without energizing the hoisting mechanism. Transfer downward is accomplished under the influence of gravity utilizing only the power required to control down valve solenoids and to operate the door motor. Ancillary operating equipment can be deenergized as in the case of hall call and car call stopping circuits, or can be maintained active by the emergency power, as in the case of position indicators; however the baring of operation of the pump motors employed in hoisting the elevator greatly reduces the demand imposed on the emergency power source and enables emergency service to be afforded with emergency power source of a capacity much reduced from that of traction type elevators.

An object of the invention is to improve elevator service under conditions where the main power source ofa system has failed.

Another object is to move hydraulic elevators to a landing to permit occupants to depart from the elevators where only limited power is available following a failure of a main power source.

1 A further object is to control the descent of hydraulic eleva tors to a predetermined landing where the main power source has failed.

SUMMARY OF THE INVENTION In accordance with the above objects one feature of this invention involves disconnecting the motor for the hoisting pump ofa hydraulic elevator in response to the transfer from a main power source to a source of emergency power.

A second feature is the disconnection of hall call and car call controls for an elevator transferred from a main power source to an emergency power source whereby manual call registering means are made ineffective.

A third feature involves means to set a car to run to a given station automatically when it is transferred from a main power source to an emergency power source.

A further feature resides in controls for operating down valves of a hydraulic elevator when it is transferred from a main power source to an emergency power source and which maintain safety features during such operation.

DESCRIPTION OF THE DRAWINGS The above objects and features will be more fully appreciated from the following detailed description when read with reference to the accompanying drawings in which:

FIG. I is a combined hydraulic schematic diagram and an across-the-line wiring diagram of a portion of the electrical controls for a hydraulic elevator according to one embodiment of the invention; and

FIG. 2 is an across-the-line diagram of additional electrical controls which cooperate with those of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT The electrical circuits are depicted in across-the-line form to facilitate their understanding. Actuating coils of relays and motors are shown in horizontal bands which are indexed in the right-hand margin to a numbered line location. Relay coils are correlated to their line location by reference characters set forth in the margin in horizontal alignment with the coil symbols of the diagram. The contacts actuated by the relays are not shown physically related to the coils, but rather are shown in alignment with the elements they control. The contacts are related to their coils by the index such that each contact shown which is actuated by an illustrated coil is indicated by the notation in the right-hand portion of the index of its line location adjacent the coils reference character. Line numerals for back contacts, those which are closed when the relay armature is dropped out and are opened when the relay armature is pulled in, are set forth underlined in the index. Front contacts, those normally open, and closed when the relay armature is pulled in, have their line locations set forth in the index without underlining.

Correlation of the hydraulic circuit and electrical circuit is accomplished by showing dashed lines between the pump motor and a schematic representation of the impeller and between the control valves and the solenoids which control those valves.

As a further aid in understanding the present invention, tables listing in alphabetical order the short functional names of the relays, their corresponding reference characters, and the line locations for those coils shown are set forth in Table A and names and characters for those contacts for which no coils are shown are set forth in Table B:

TABLE A Functional Name Line Symbol.

(1B. (az-(Jall. 51 l).. lmwn l)i| ill El I-Tmr-rt cnc l'rmor. 11 Elk. Auxiliary IIIxlt-IL'Pnf) lou'vn. 1: LI). Law-l Down... 43 Ll) D1101 Zone. 4'. LI: Lnvnl L'p. 41 SI). llown IIILIlSpffC'I... 34 BL. l'p lligh Sp4: rl 33 TL lliphSpr-erl.... 22 L' I'pDirectiun. 14 [IDA I'p or Don-11L ..tion 32 if) to T0. 1 t to Top Floor Car Call, 5046 TABLE ll Functional Name Line Symbol:

(1L ])oorCl0sc..... ('Sl) .(ar Slowdown... [)CL Door Close Limit lmwnbircction Locking Snlvctorlntcruptoru lworOpen L'pDlrection Locking.............

FIG. I shows a hydraulic elevator comprising a car 61 supported in a column of oil or other suitable hydraulic fluid contained in a jack cylinder 62 into which a plunger 63 telescopes. A pump 64 draws the fluid through a hydraulic line 65 from reservoir 66 and advances it to a manifold 67 from which it is returned through up valve 68 and return line 69 to tank 66. In order to raise the car, the up valve 68 closes causing the fluid in manifold 67 to pass check valve 71 and flow through line 72 to jack 62 Check valve 71 hydraulically locks the elevator in position. It has a spring loaded piston arrangedv at 24, DV at and DLV at 18 as represented by the dashed lines 75, 76 and 77 representing actuating linkages. Up valve 68 is the only valve employed to operate the elevator in the up direction. it serves as a starting valve for smooth acceleration, an up leveling valve providing a stabilized leveling speed and a soft stop, and a relief valve to prevent shock when the pump is started. The down valve opens and closes at a controlled rate to control the rate of fluid flow from the jack without shock or hammer in the system, while the down leveling valve is a smaller capacity version of the down valve to bring the car level with the floor by finer control of the fluid flow.

In normal operation a signal requiring travel upward starts motor 78 driving pump 64 to force fluid through up valve 68 to return to tank 66. The up valve slowly closes so that the fluid is forced against the closed check valve 71 to open that valve and pass the fluid to the jack 62 gradually increasing the rate at which the lifting force is applied to the jack. When the up valve is completely closed, all fluid issued by the pump is passed to the jack and the cab 61 is raised at its maximum speed.

Just prior to the arrival of the car at floor level, a car position sensing device, which may be a magnetically closed switch, is actuated to initiate its slowdown. The up valve 68 is opened partially thereby permitting a portion of the fluid issuing from pump 64 to return to tank 66 while the remainder is passed by check valve 71 to jack 62. When the car is level with the floor, the motor is stopped. The up valve is fully open at this time and the hydraulic system is conditioned as shown in H0. 1. As the fluid flow decreases, the check valve closes gradually so that it is fully closed before the fluid can reverse its flow, thereby avoiding shock or hammer in the line. The car is supported at rest on the column of fluid in the jack.

Down travel is instituted by first gradually opening down leveling valve 74 and then gradually opening the down valve 73 to their fully open positions so that the weight of the car and its load forces the fluid from the jack 62 through the valves to return line 69 and the tank. Acceleration in down travel depends on the rate at which the valves open and the friction between the packing and plunger. As the car approaches a landing, a leveling device is actuated to slowly close the down valve 73 so that in the final approach to the floor only the down leveling valve 74 is open to pass fluid from the jack to the tank. This slows the car to leveling speed. When the car is level with the floor, down leveling valve 74 is closed to close all paths from the jack to the tank and hold the car at the floor.

Electrical control of the hydraulic operation, described in greatly simplified form above, is by means of the circuits shown in FIGS. 1 and 2 and is in response to the registration of calls for service on either hall call devices (not shown) or car call devices such as push buttons 79 and 81 for the first and top floors respectively. Power is normally supplied from an alternating current source at terminals 82 to emergency power transfer switch 83, a triple pole double throw switch, and leads 84 and 85. Pump motor 78 is energized through up direction relay contact U at 10 from leads 84 and 85. The remainder of the disclosed controls is energized from rectifier bridge 86 connected across leads 84 and 85 to supply direct current to leads 87 and 88.

Emergency power relay E? at 11 is connected and energized across leads 87 and 88 through pole 89 of switch 83 when it is positioned to connect the system to the primary power source and is deenergized when switch 83 is transferred to the emergency power source at terminals 91 since pole 92 is connected to no power source. Auxiliary emergency power relay EPX at 12 is normally deenergized by open back contact EP. Relays EP and EPX cooperate to transfer the elevator controls to the emergency power operating mode when the system is transferred from its primary power source at 82 to its emergency power source at 91 by switch 83. in practice, switch 83 can be controlled either automatically or manually. With relay EP deenergized its closed back contact at 12 enables relay EPX, its open front contact at 14 disables up direction relay U preventing the pump motor from operating, its open front contact at 46 disables the car call buttons to prevent manual registration of car calls by passengers, its closed back contact at 48 automatically registers a car callfor the first landing, and its open front contact at 54 disables the hall call registration circuits 93 and the hall lantern controls. Relay EPX prevents repetitive operation of the automatic registration of the first landing car call. It is energized on the first registration by the coincidence of closed contacts EP and 1C at 12. Open back contact EPX at 48 prevents further automatic car calls while closed contact EPX at 13 seals relay EPX until primary power is restored to the system through switch 83 to energize relay EP and open its back contact at 12.

Movement of the elevator is controlled by the operation of the hydraulic valves 68, 73 and 74 and pump motor 78 all of which are controlled by up direction relay U at 14 and down direction relay D at 19. The direction relays U and D are controlled by leveling relay contacts LDO, LU and LD, safety switches 94 and 95, high speed relay contacts SU and SD, and interlocking contacts U and D. Gate contact 94 is closed when the car door is closed. The landing door contacts 95 (only one of which is shown) are closed when all landing doors are closed and locked. These safety switches complete a circuit to junction 96. When the car is outside a leveling door zone for a landing at which it is to stop back contact LDO at 14 is open and front contact LDO at 18 is closed. The direction relays are then energized through gate switch 94, landing switch 95, junction 96, contact LDO at 18, and for up travel, up high speed relay contact SU at 15, emergency power relay contact EP and interlocking down direction relay back contact D at 14 to energize up direction relay U. For down travel the energization is through down high speed relay contact SD at 17 and interlocking up direction relay back contact U at 19 to down direction relay D.

When the car is in the leveling door zone for a landing at which it is to stop, back contact LDO at 14 is closed and contact LDO at 18 is open so that up direction relay U is energized when relay LU is deenergized to close back contact LU and relay LD is energized to close contact LD at 14. This condition prevails while the car is below landing level. When the car is above landing level, down direction relay D is energized by closed back contact LD of deenergized relay LD and closed contact LU at 14. When the car is level with a landing, both of relays LU and LD are energized to open their back contacts in the paths to relays U and D.

Up direction relay U when energized energizes pump motor 79 through closed contact U at 10, seals itself by contact U at 15, locks out down direction relay D by its open back contact U at 19, enables up valve solenoid UV at 24 by closing contact U at 24 to close that valve, and energizes up or down direction relay UDA by closing contact U at 31.

Down direction relay D when energized locks out up direction relay U by open back contact at 14, seals itself for running at 18, enables down valve solenoid DV by closing its contact D at 20 and energizes up or down direction relay UDA by closing contact D at 32.

Down valve solenoid when energized urges down valve 73 to an open position. The valves motion, as with valves 68 and 74, is retarded hydraulically (by means not shown.) to provide a gradual transition between its open and closed position. It is energized when the car is set to descend through closed gate contact 94, landing door contact 95, up and down leveling contacts LU and LD, up high speed contact SU and up direction contact U all at 24.

Down leveling valve solenoid DLV at 18 is energized with down direction relay D.

High speed relay TL is energized when either of the up high speed or down high speed relays SU or SD are energized, provided safe running conditions prevail and both up and down leveling relays are energized to close contacts LU and LD at 24. High speed relay seals in the leveling relays for the start of a car from a floor and for running past a floor by closing contacts TL at 42 and 43 when energized. It remains dropped out for releveling so that releveling is controlled by the down leveling solenoid DLV at 18 as relay D is energized and by the differential in hydraulic pressure on the input and output side of the up valve when the pump develops pressure after relay U is energized. In down releveling, valve 74 is opened to bleed fluid from the jack to the tank. In up releveling, valve 68 is at least partially closed so that the fluid pressure developed by pump 64 is applied to check valve 71 sufficiently to open that valve and pass fluid to the jack.

In FIG. 2, up or down direction relay UDA at 32 is energized whenever either of relays U or D are energized to condition the car to move. It initiates opening of the car door when dropped out (by means not shown) and complements car door operation so that direction locking circuits (not shown) and car slowdown relay circuits (not shown) are enabled during the time the car is set to run.

Up high speed relay SU at 33 and down high speed relay SD at 34 are energized. When the selector switch interrupter relay INT is energized to close its contact INT at 33, or the car slow down relay is deenergized to close contact CSD at 34 provided the appropriate direction locking relay has been energized to close up direction locking contact UL at 33 and energize SU for up travel or to close down direction locking relay contact DL at 34 and energize SD for down travel. lnterrupter relay INT (not shown) operates a bidirectional stepper switch (not shown) providing the usual floor selector function of indicating the position of the car along the hatch. It is energized three times in the travel of the car between adjacent floors, once at the midpoint to the next adjacent floor, and once at each of the slowdown points above and below the floor.

As a call is registered or conditions established by expiration ofa door time interval so that a start signal is imposed, car slowdown relay CSD (not shown) drops to close back contact CSD at 34. The calls establish direction locking, by means not shown, so that relay SU is energized through contacts CSD at 34 and UL at 33 or relay SD is energized through contacts CSD at 34 and DL at 34. Relays SU or SD condition the controls to energize direction relay U or D when the doors are closed. When the running car reaches the slowdown floor, it is conditioned to stop if a call for the floor and service direction is registered before or while relay INT is energized since relay CSD is energized so that upon the dropout of relay INT as it passes the slowdown point the registered call retains CSD energized (by means not shown) thereby deenergizing SU or SD.

With both relays SU and SD deenergized relay TL at 22 drops to enable the leveling switches 97, 98 and 99 to control the leveling relays LU, LD and LDO at 41, 43 and 42 respectively by opening contacts TL at 42 and 43. The leveling switches 97, 98 and 99 are shown in the condition they assume when the car is level with a landing. Each switch is mounted on the car in vertical array and is normally closed when out of the range of a ferromagnetic vane (not shown) mounted in the hatch. Door zone switch 98 is centered between level up switch 97 and level down switch 99. The vanes are each of a length and so positioned to span most of the distance between switches 97 and 99 so that the switches are both just out of the range of influence of the vane for a landing when the car is level with the landing.

A second set of vertically aligned hatchway vanes cause notching switch 101 to be opened at the midpoint between each landing and at the slowdown point above and below each landing. This switch momentarily deenergizes stepper notching relay SN to permit it to close its back contact SN at 40 and cock the selector drive for its advance. The drive is advanced as switch 101 is closed to pickup SN and open back contact SN at 40.

The ascending car approaching a landing first opens and closes contact 101 to define the initiation of slowdown by dropping relay SU to deenergize up valve solenoid UV at 24 and initiate gradual opening of up valve 68. Motor 78 continues to operate at this time and sufficient hydraulic pressure is imposed on valve 68 to prevent its complete opening. When the car reaches the up leveling point, switch 97 is opened. Since relay TL dropped at slowdown contacts TL at 42 and 43 are open and relay LU is dropped to close its back contact at 14 and to open its contacts at 19 and 24 to prepare for final leveling to the floor. Further travel of the car brings switch 98 into the range of influence of the leveling vane to open that switch and drop relay LDO. Relay LU remains energized at this time. The final leveling circuit is established through back contact LDO at 14 while open contact LDO at 18 disconnects the normal running circuits for the up direction relay U. As the car levels relay U is dropped by the reenergization of relay LU since the car moves to a position carrying switch 97 above and out of the range of influence of the leveling vane. This stops the pump motor 78 to stop the car.

If the car overshoots and travels above the level position, switch 99 is brought into the range of influence of the leveling vane to open its contacts and drop level down relay LD at 43. This opens contacts LD at 14 and 24 with no effect, and closes back contact ID at 19 to energize down direction relay D at 19 and down leveling valve solenoid DLV at 18 through closed back contacts LDO at 14, and LD at 19, closed contact LU at 19 and closed back contact V at 19. The down leveling valve 74 gradually opens permitting the car to sink as fluid flows from the jack through valve 74 to tank 66.

A descending car operates the leveling switches in the inverse order. The car movement to the down slowdown point opens notching switch 101 to drop relay SN and thereby drop relay SD and TL and deenergize down valve solenoid DV at 24. The down valve 73 gradually closes to slow the flow of fluid from jack 62 to tank 66 and slow the car descent. As the car reaches the leveling zone, down leveling switch 99 is opened to drop down level relay LD at 43. Contacts LD at 14 and 24 open and back contact LD at 19 closes to condition the leveling controls for operation. Further descent of the car opens door zone switch 98 to drop relay LDO for setting the final leveling control by closing back contact LDO at 14 and opening contact LDO at 18. When the car is level with the landing, switch 99 is below the range ofinfluence of the leveling vane and switch 97 has not yet entered that range, hence contacts of those switches are closed while contacts of switch 98 are open and relays LU and LD are energized while relay LDO is deenergized. Down valves 73 and 74 are closed since their solenoids are deenergized and the car is held on the column of fluid in jack 62.

With the car at a landing the door controls 102 are set to open the door and after a suitable load transfer interval, close the door (by means not shown). These controls include door open relay DO and door close relay CL controlling the series field 103 and shunt field 104 of the door motor having armature ARM. Thus with contacts CL at 36 and 38 closed, the door is driven in a closing direction and with contacts OP closed at 35, 36 and 37 the door is driven in an opening direction.

Typical car call registration circuits are shown at lines 46 to 51. When operating under normal power contact EP at 46 is closed to connect lead 87 to lead 105 for the holding circuit of each of the car call relays but that for the first landing and to lead 106 for the circuit to the common car call relay CB at 51. The arrowheaded extension on lead 105 indicates its connection to car call relays for other floors in the same manner as for relay TC. Relay C8 is energized when any car call button is depressed to close its second set of contacts to lead 107. C13 abbreviates the door open interval when an entering passenger registers his car call (by means not shown). Each car call relay has a set and reset coil indicated by the suffix letters S and R respectively. Registration of a call energizes the set coil TCS at 46 to seal the relay as at contact TC at 47. When the car is at a landing. as indicated by the selector brush 108 in engagement with the landing contact T for the top landing, and when the car door is initially opened to energize door close limit relay DCL and close its contacts DCL at 47. While a car call is registered, the indicator lamp at 109 is lighted.

First floor car call operation differs in the automatic car call registration feature provided through back contacts EP and EPX at 48. The circuit for manual call registration through push button controlled contacts 79 is paralleled by a circuit which registers a car call for the first floor when the system has been switched to emergency power operation from source 91. Failure of the main power drops relay EP at 11 to close back contact EP at 48. Relay EPX remains dropped during normal operation. When emergency power is applied by operation of switch 83 it energizes lCS at 49 through lead 87 back contacts EP and EPX at 48 and lead 111. Closure of Contact [C at 12 energizes relay EPX to provide a seal at 13 and open the automatic car call registration circuit at 48.

Under emergency power operation the demands imposed on the supply at terminals 91 is limited by excluding operation of the pump motor 78 and the car automatically runs to the first floor, opens its doors and, with automatic door reclosing in the system, automaticallycloses the doors after a suitable unloading interval. Although the emergency power source is connected to the normal operation circuits by switch 83 and direct current is applied to leads 87 and 88 relay EP is dropped by the disconnecting of lead 113 from lead 112 at pole 89 of switch 83 to restrict power consumption.

Open contact EP at 14 deenergizes relay U so that contact U at opens the circuit to the pump motor and the up valve remains open since its solenoid UV is deenergized by open contact U at 24. No power is required for hall lanterns or for the hall call registration circuits, hence these circuits are' disconnected by opening contact EP at 54. Only the first floor car call circuit remains effective to control the travel of the car to the first floor and the remaining car call circuits are disconnected by opening contact E? at 46.

With the emergency power supply connected the system automatically registers a car call for the first floor. This call actuates the direction selecting and locking circuits at 52 (by means not shown) according to conventional control means for normal operation to set the car for down travel if it is above the floor for which the car call is automatically registered. The controls for down travel of the car are energized so that the down valve solenoid DV and down leveling valve solenoid DLV are controlled, the down high speed relay SD is energized to open those valves and permit fluid to flow from the jack 62 to the tank 66. Such flow is in a normal down travel control sequence since the leveling and selector advance controls operate in response to the descent of the car so that as the car approaches its slowdown zone for the first floor relay SN drops to energize relay CSD and when relay SN is rcenergized it drops relay INT, thereby opening all energizing paths for relay SD at 34. The solenoid DV is deenergized to begin the slowdown of the car by permitting down valve 73 to close gradually and relay TL is dropped to enable the leveling relays LU, LDO and LD. When upon further descent of the car into the leveling zone LD and LDO are dropped relay D and solenoid DLV are deenergized. Down leveling valve 74 is then controlled by relay LD so that upon the descent of the car to the level position with the first floor relay LD is energized to open its back contact LD at 19 and deenergize the valve solenoid DLV at 18. This stops the car at the floor and holds it on the column of fluid remaining injack 62.

The leveling relays can be arranged to control the door controls 102, for example, so that upon the reenergization of relay LD while relay LDO is deencrgized the door open relay OP is energized to cause the car and hail doors to be driven open. The door controls 102 can further include a timer which causes the door close relay CL to be energized and drive the door closed after expiration of the usual door open interval.

The system maintains the car at the floor for which the automatically registered car call is provided until normal power is restored and switch 83 is connected to terminals 82. At that time relay EP is energized from lead 87 through lead 112, pole 89, lead 113 and coil E? to lead 88. Back contact E? at 12 opens to drop relay EPX thereby resetting the emergency ower actuated automatic car call circuit for the first floor. ack contact HP at 48 opens to open the automatic car call circuit, Closure of contact E? at 14 enables the circuit for the up direction relay U so that the car can be run upward. The car call circuits are enabled by closing contact EP at 46. Hall call registration circuits 93 and the hall lantern control circuits are restored by closing contact E? at 54. Thus the system is returned to normal operation when relay EP is energized and is conditioned to recycle for emergency power operation.

l claim:

1. A hydraulic elevator, 21 primary source of electrical power, secondary source of electrical power, a fluid pump for imposing a lifting force on said elevator, an electrical motor for said pump, electrical circuits for controlling the ascent and descent of said hydraulic elevator, means to connect selectively said primary source of electrical power and said secondary source of electrical power to said electrical circuits, and means responsive while said primary source of electrical power is disconnected from said electrical circuits for preventing operation of said electrical motor by power from said secondary source.

2. A system according to claim 1 including an up valve to control the application of fluid causing said elevator to ascend, a solenoid in said electrical circuits for operating said up valve, and means responsive while said primary source of electrical power is disconnected from said electrical circuits for preventing operation of said solenoid to a condition applying fluid to cause said elevator to ascend by power from said secondary source.

3. A system according to claim 1 wherein said electrical cir cuits include manually operable call registering means for registering calls for service at floors served by said elevator, and means responsive while said primary source of electrical power is disconnected from said electrical circuits for preventing operation of said manually operable call registering means.

4, A system according to claim 1 including means responsive to the connection of said secondary source of electrical power to said electrical circuits for automatically registering a call for a floor to cause said elevator to run to said floor.

5. A system according to claim 1 including a down valve to control the flow of fluid causing said elevator to descend, a solenoid in said electrical circuits for operating said down valve, and means responsive while said secondary source of power is connected to said electrical circuits for operating said down valve solenoid to cause said elevator to descend to a given landing.

6. A system according to claim 5 including means to automatically register a call for service by said elevator to a predetermined landing in response to the connection of said secondary source of electrical power to said electrical circuits, and wherein said means for operating said down valve solenoid is responsive to said call registering means to cause said elevator to descend to the landing of said call registering means.

7. A combination according to claim 5 including a door for said elevator, means to sense the position of said elevator at said given landing, and means responsive to said positioning means when at said given landing for driving said door open.

8. A hydraulic elevator, a pump for developing elevator lifting force in hydraulic fluid; electrically energized means for controlling the application of hydraulic lifting force to said elevator; electrically energized means for controlling the descent of said elevator under the influence of gravity; a primary source ofelectrical power; a secondary source of electrical power; means for selectively coupling said electrically energized means to said primary source of power and to said secondary source of power; and means responsive while said secondary source of power is connected to said electrically energized means for preventing the application of hydraulic lifting force to said elevator. 

